Copying all the data from a store isn't a big problem, copying a store without creating inconsistent state while the application continues to run is the challenge I thought the user was interested in. If you do it at the application level within a transaction (even if it did fit in memory) you would either implicitly halt all activity or constantly be aborted by any write operation anywhere in the db.

While there is not an 'elephant' level way to do live backups, each underlying data store has it's own methods as pointed out by Henrik and Alex for the SQL cases.

Berkeley DB also supports low-level hot backups if you know that your OS reads file pages atomically. (http://www.oracle.com/technology/documentation/berkeley-db/db/ref/transapp/archival.html ) For an example see the source code for db_hotbackup in the BDB distribution.

Ian

On Dec 11, 2007, at 7:43 AM, Alex Mizrahi wrote:

IE> policy for object creation and just copy all the objects from one
IE> store to another.

if bdb has serializable isolation level be default, woudn't it be enough
just to copy data within transaction?



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